The invention relates to a free-piston unit. A unit of this type is known from NL 6814405. The drawback of the known device is that the first, low pressure and the second, high pressure are dependent on the use of the device or the use which is being made at a specific moment of the hydraulic energy which is generated. Consequently, the unit is difficult to control, since the forces acting on the plunger cannot be set independently of the low or high pressure; with the result that the energy supplied to or extracted from the combustion piston is difficult to regulate. To avoid this drawback, the unit is designed in yet another way. It is thus possible to set the energy supplied to or extracted from the combustion piston independently of the first pressure and/or the second pressure, so that accurate control of the combustion process and also part-load operation are possible.
According to a refinement, the unit is designed in yet another way. It is thus possible to set the amount of energy supplied to the combustion pistons so that the combustion process can be controlled more successfully.
According to a refinement, the unit is designed in yet another way. This makes it easy to set the third pressure.
According to a refinement, the unit is designed in yet another way. This ensures uninterrupted use of the unit.
According to a refinement, the unit is designed in yet another way. In this way, it is easy to drive rotationally driven auxiliary equipment; such as a dynamo, a fan and the like.
According to a further refinement, the device is designed in yet another way. This improves the operation of the hydraulic transformer, since fluctuations in pressures and fluid flows are evened out.
According to one embodiment, the device is designed in yet another way. As a result, the fluid flow through the hydraulic transformer is always equal to the volume pumped to the second fluid source by the unit, so that this volume can also be known in the control unit.
According to one embodiment, the device is designed in yet another way. In this way, it is easy to set the force exerted on the plunger.
According to one embodiment, the device is designed in yet another way. As a result, the supply of fluid from the unit to the second fluid source always takes place via the hydraulic transformer, so that the supply of fluid is more or less free of pulsations which limits the energy losses and prevents pressure pulsations if there is no accumulator in the system connected to the second fluid source. It is also possible for the fluid flow to be directly adapted to the fluid flow extracted by the consumers.
The invention also comprises a device in yet another way. This makes the flow of fluid to the second fluid source more uniform.